1. Field of the Invention
The present invention relates to a method for driving a development unit for an image forming apparatus, and more particularly, to a method for driving a development unit for an image forming apparatus which can simultaneously remove drip lines generated during development from the respective developing devices for colors Y (yellow), M (magenta), C (cyan) and K (black).
2. Description of the Related Art
An image forming apparatus reproduces characters or images onto a recording medium according to transferred characters or picture image data signals. An image forming apparatus generally includes a photoreceptor member, e.g., a photoreceptor drum or a photoreceptor belt, which forms a latent electrostatic image, a charging unit which charges the photoreceptor member, and an exposure unit which forms a latent electrostatic image having a predetermined pattern by scanning light onto the charged photoreceptor member. An image forming apparatus also includes a development unit which develops the latent electrostatic image by supplying a development medium, e.g., a toner or a developer liquid, on the exposed latent electrostatic image, and a transfer unit which transfers the developed image to the recording medium by applying pressure or heat.
FIG. 1 is a schematic diagram showing a general image forming apparatus. Referring to FIG. 1, the image forming apparatus includes a photoreceptor belt 104 installed to circulate around first, second and third belt rollers 101, 102 and 103. A discharger 105 removes charges remaining in the photoreceptor belt 104, whereas charger 106 newly charges the photoreceptor belt 104. Exposure units 107, 108, 109 and 110, each having a laser scanning unit (not shown), scan a laser beam for the purpose of selectively discharging the image forming portion of the photoreceptor belt 104 thereby forming an image-shaped pattern. Development units 111, 112, 113 and 114 for respective colors Y, M, C and K, develop the latent electrostatic image formed on the photoreceptor belt 104. A drier 115 dries the developer liquid supplied to the latent electrostatic image. Finally transfer unit 116 transfers an arbitrarily developed image formed on the photoreceptor belt 104 to a recording medium 117 such as a sheet of paper or a film.
The development unit 111 includes a developing roller 111a for coating the developer liquid on the photoreceptor belt 104, a developer liquid supplier 111b which supplies the developer liquid to the developing roller 111a, and a cleaning roller 111c which removes developer liquid embedded on the rear surface of the developing roller 111a. The developer liquid develops latent electrostatic images formed on the photoreceptor belt. The development unit 111 also includes, first and second squeegee rollers 111d and 111e which remove the developer liquid remaining on the photoreceptor belt 104, as well as includes first and second blades 111f and 111g which remove the developer liquid embedded on the first and second squeegee rollers 111d and 111e. The development unit 111 further includes a developer liquid recovery container 111h for recovering the developer liquid removed by the cleaning roller 111c and the blades 111f and 111g.
The drier 115 includes a heating roller 115h which dries the developer liquid embedded on the photoreceptor belt 104.
The transfer unit 116 includes a transfer roller 116t disposed close to the first belt roller 101, wherein the photoreceptor belt 104 is interposed therebetween to reciprocally rotate, thereby transferring the image on the photoreceptor belt 104 to the transfer roller. The transfer unit 116 also includes a fixing roller 116p disposed close to the transfer roller 116t to reciprocally rotate therewith, thereby fixing the image transferred to the transfer roller 116t onto the recording sheet 117.
In the image forming apparatus having the aforementioned configuration, when the developing roller 111a of the development unit 111 makes contact with the photoreceptor belt 104 to supply a developer liquid thereto and is then removed from contact with the photoreceptor belt 104, a drip line 200d having a shape in the form of a dripping fluid is formed on the photoreceptor belt 104, as shown in FIG. 2. The drip line 200d causes poor printing such as blotted images. Conventionally, the drip line 200d is removed by the first and second squeegee rollers 111d and 111e. In other words, as shown in FIG. 2, if the drip line 200d is formed on the photoreceptor belt 104, the first squeegee roller 111d is first rotated in the same direction as the direction in which the photoreceptor belt 104 travels, until the drip line 200d gets closer to the first squeegee roller 111d. Then, as shown in FIG. 3, the first squeegee roller 111d is reversely rotated and the first blade 111f is brought into contact with the first squeegee roller 111d. Accordingly, developer liquid 200 is caught in the first blade 111f and drops downward. As a result, the drip line 200d is removed.
According to the conventional drip line removing method, the drip lines of the respective development units 111, 112, 113 and 114 for the colors Y, M, C and K are sequentially removed. Thus, development units and power transmission mechanisms are separately provided for each. In other words, four frames, four motors, four shafts, eight cams and each power transmission system must be provided for the respective units. Accordingly, the overall configuration becomes complex, which increases the fabrication cost as well as makes maintenance and repair difficult.